The present invention disclosed herein relates to a semiconductor device, and more particularly, to a phase change memory device and a method of forming the same.
Phase change materials are capable of embodying at least two recognizably different states—for example, a crystalline state and an amorphous state, plus at least one or more intermediate states, and thus may be used as materials in memory devices. An amorphous state displays a higher specific resistance than a crystalline state, and intermediate states display specific resistances between those of the amorphous and crystalline states.
Phase changing of a phase change material may occur according to changes in temperature, which may be induced, for example, through heating a resistor employing a conductor connected to a phase change material. Heating of a resistor may be achieved through an electrical signal (a current, for example) applied to both ends of the phase change material. The resistance value is related to the to both ends of the phase change material. The resistance value is related to the contacting area between a phase change material and a conductor connected thereto, where the smaller the contacting area is, the greater the resistance value becomes. Based on the same current amperage, the greater the resistance value, the more effective the heating of a phase change material is. Thus, to achieve a phase change memory device having low operating power requirements, the contacting area between the phase change material and the conductor connected thereto needs to be minimized.